Biocatalytic production of adiponitrile and related aliphatic linear α,ω-dinitriles.

Linear α,ω-dinitriles are important precursors for the polymer industry. Most prominently, adiponitrile is produced on an annual scale of ca. 1 million tons. However, a drawback of today's dominating process is the need for large amounts of highly toxic hydrogen cyanide. In this contribution, an alternative approach towards such linear dinitriles is presented based on dehydration of readily available α,ω-dialdoximes at ambient conditions by means of aldoxime dehydratases. In contrast to existing production routes this biocatalytic route enables a highly regio- and chemoselective approach towards dinitriles without the use of hydrogen cyanide or harsh reaction conditions. In addition, a selective synthesis of adiponitrile with substrate loadings of up to 100 g/L and high yields of up to 80% was achieved. Furthermore, a lab scale process on liter scale leading to > 99% conversion at 50 g/L underlines the potential and robustness of this method for technical applicability.

Retention-time prediction for polycyclic aromatic compounds in reversed-phase capillary electro-chromatography.

Log Po/w based models are often used for the retention time prediction of reversed phase liquid chromatography. Here, we present the investigation of the applicability of log Po/w based retention time predictions for the separation in capillary electro-chromatography (CEC). A test set of five polycyclic aromatic hydrocarbons was separated using two different stationary phases with three different mobile phases each. The resulting retention times were correlated with the experimental log Po/w values as well as with calculated log Po/w values. The used methods include quantitative structure property relationship (QSPR) models as well as molecular dynamic methods such as the linear interaction energy (LIE) or the Bennett acceptance ratio (BAR). The results indicate that rigorous simulation models are capable of accurately reproducing experimental results and that the electrophoretic mobility of analytes in CEC separations leads to significant deviations in the retention time prediction.

Probing the aglycon binding site of a beta-glucosidase: a collection of C-1-modified 2,5-dideoxy-2,5-imino-D-mannitol derivatives and their structure-activity relationships as competitive inhibitors.

A range of new C-1 modified derivatives of the powerful glucosidase inhibitor 2,5-dideoxy-2,5-imino-D-mannitol has been synthesised and their biological activities probed with the beta-glucosidase from Agrobacterium sp. Ki values are compared with those of previously prepared close relatives. Findings suggest dramatic effects exerted by the aglycon binding site on substrate/inhibitor binding.